From my understanding - and which experience seems to confirm so far - low strength fissures generally require lower charges than higher strength fissures to gain a comparable result. That said, I always try to start with a strong blow into a low strength fissure, then, depending on the result shown in the diagram, a weak to medium blow into another low strength fissure.
For fine tuning (if only one or two rows in the diagram are left) I would chose a high strength fissure for adjusting cause these don't overcharge that easily. With this method I often get away with even just two loads. But that's mainly down to personal preferences I guess, not saying that's the optimal procedure. I'm sure you can do it differently as well.
One hint for those new to deep core mining and to help them to prevent the same beginner mistakes I did at first: You need to scan the rings with a surface scanner at first to find the hot spot(s). This is something you only need once, it stays persistent then. BUT - don't think you could spare the surface scanner from now on! You still need them, otherwise you won't see any hotspots at all.
The high strength to tune is a good tip... I usually just put, low to low or medium to medium as well, it all works the same, but with the buggy charge reticle the high strength would be safer. I find it confusing that you need to have the DSS on board to find something you already found. Do you need one to find volcanic activity you already found with the DSS?
How many resource chunks exposed do you get without limpets on average? When i blow up a asteroid i get a message saying 10 to 16 resource chunks exposed
Also i found that asteroids seem to have different thresholds for cracking open, i always start with high charging low strength fissures and then tweaking with low or medium charges to higher strength fissures.
in some cases I have been able to crack a roid with just 2 high charges to 2 low strength fissures or 1 low strength and 1 average strength fissure with high charges
About the same, the only issue is if you go over optimal as you can't select a charge and disarm it. Also, you don't know what is in the roid, you just can tell, because it has fissures and you can visually see these, that it has core deposits. If you're in a hot spot, most of the core depositis will be the new stuff by about 2/3 thirds of the time. The other thing, because you can't select the charge, you have to wait out the full time and can't detonate now.
So for doing small ships, you don't need limpets of any kind when hunting core deposits, this makes ships like the Adder, Cobras and Keelback (small medium) viable and quite profitable as miners. When I'm mining in my Krait I will take a 3A collector and a 3A prospector along for the convenience factors. I enjoy using the Keelback as a miner, sessions are relatively short and very profitable.